Process of impregnating material fibres with zinc thiocyanate and article produced thereby



United States Patent O and PRGCESS OF IMPPEGNATENG P-f-lATERIAL FIBRES WITH ZIN C THIOCYANATE AND ARTICLE PRO- DUCED THEREBY No Drawing. Application September 2, 52, Serial No. 307,577

Qiaims priority, application Germany geptember 4, 1951 10 Claims. (Ci. 117138.5)

This invention relates to the treatment of materials with a fungicide. In particular the invention is directed to inhibiting vegetable and animal fibers in stranded or woven form against molds by impregnating the fibers with zinc thiocyanate.

In humid and warm climates, materials composed of vegetable or animal fibers are subject to the destructive action of various molds, particularly when stored for extended times. Fungicides used heretofore have been of limited application as some of them adversely affect the color of the materials to which they are applied, some affect the strength of the materials, and some are poisonous to warm blooded animals. Again some evaporate too quickly, and some wash out too soon to be fully effective.

The objects of this invention are to produce stranded or woven fibrous organic materials impregnated with a fungicide which is non-toxic to warm blooded animals, non-deleterious, and of lasting effect.

In general, these objects are obtained by impregnating the materials with solutions of zinc thiocyanate, which has the disinfectant, fungicidal, and rot preventative actions of zinc combined with those of the cyanate. This compound, zinc thiocyanate, is practically non-poisonous to warm blooded animals, non-evaporating, odorless, and non-damaging to materials made from fibers of vegetable or animal origin. These are fibers of natural origin as distinguished from synthetically produced fibers from synthetic resins and the like. When used in concentrations greater than necessary for fungicidal purposes, the zinc thiocyanate gives the materials fire resistant properties. Materials so treated will neither continue to burn nor to smolder after being taken from a flame of fire.

in accordance with the invention, the impregnation of the materials with zinc thiocyanate can be combined with other Well-known textile treatment processes, such as waterproofing or rendering the fabric water-repellent, by adding corresponding substances such as aluminum sulphate, or titanium salts, to the zinc thiocyanate solution without destroying or diminishing the fungicidal effect of the zinc thiocyanate. It is also possible to add Water-soluble synthetic resins to the zinc thiocyanate solution, in order to impregnate the fabrics completely. For this purpose the incompletely reacted condensates of urea-formaldehyde resins have proved to be particularly suitable, which after condensation and drying can be further subjected to a final thermal treatment for the purpose of hardening.

Instead of urea, the derivatives of urea such as dicyanodiamide (cyanoguanidine), melamine (2,4,6-triamino-s-triazine), or the like may be employed. It has been shown that such water soluble preliminary condensates fiocculate, depending on their composition and possibly by adding an electrolyte. In these cases the soluble synthetic resin preliminary condensate cannot be added to the zinc thiocyanate solution because these synthetic resins would precipitate before the actual impregnation of the fabric. In aceutuance with this invention the fabric is first soaked in a water solution of the synthetic resin preliminary condensate, and then impregnated with the zinc thiocyanate solution. In this manner the zinc thiocyanate has a flocculatiug effect on the synthetic resin which is deposited in a particularly fine uniform and adherent distribution in the material, without however diminishing or affecting the action of the zinc thiocyanate on the fibers.

The term textile is used in the specification and claims to include stranded materials such as rope, as well as woven, knitted, and felted materials composed of fibers of animal or vegetable origin.

The process in accordance with this invention, employing either zinc thiocyanate alone or in combination with other agents used in the treatment of textile materials, is illustrated by the following examples:

1. Hemp rope is sprayed and completely saturated with a 4% zinc thiocyanate solution, which may also have a wetting agent added thereto, and then is air dried with frequent change of position. It is rendered resistant against an attack of mold fungus and other causes of rotting, Without affecting its other properties.

2. Cotton blankets are saturated with a solution containing 4% zinc thiocyanate and 5% aluminum sulphate, and then are air dried, and thereafter heat treated for one hour at temperatures between 90 and 100 C. By adding aluminum sulphate the blankets are not only resistant against fungus and rotting, but are also rendered water resistant.

3. A tarpaulin made of sisal is sprayed with a solution containing 6% zinc thiocyanate and 8% of a soluble double salt of titanium such as (NH4)2[TiO(SO4)3l.H2O, or (NH4)z[TiCls].2HzO, and after drying is given an after treatment with a 4% soap solution. Similar zirconium salts may be used. The tarpaulin is then resistant against rot and fungus and furthermore possesses excellent water repellent properties.

4. Cotton curtains are treated with a solution containing 15% zinc thiocyanate and 4% basic zirconium acetate, thereafter in a moist or dry state sprayed with a practically neutral solution of an alkali salt of stearic acid or oleic acid or abietic acid. After this treatment the curtains are not only resistant against fungus and waterproof, but also rendered resistant against inflammability and smoldering.

5. A water soluble incompletely reacted condensate is prepared by reacting about parts of urea in parts of Water and 0.5 part of glacial acetic acid with 6 parts of acrolein at a pH of 4.5 and a temperature of about to C. This preliminary condensate is thereafter subjected to a further condensation treatment with an addition of 187.5 parts of a 30% by volume solution of formaldehyde for 20 minutes at a temperature between and C. at a pH between 7.8 and 8.2 (adjusted by an addition of soda lye). The thus formed reaction product is first diluted with water at the rate of 1 to 2, whereupon 6% of a 40% solution of AlC13.5H2O and 5% of a 10% solution of zinc thiocyanate are added. A thin coating of the resin-zinc thiocyanate solution is deposited on webs which are then rendered resistant against rotting and stress. The further condensation of the mixture may be accelerated by employing higher temperatures, for instance, of about to C., with or without additional pressure.

6. Twill is saturated with a solution containing 10% zinc thiocyanate, then shortly exposed to air and in a moist or dry state soaked in an aqueous solution (1:1) of a condensation product of dicyandiamide and formaldehyde. This solution is prepared by condensation of 74.5 kgs. of dicyandiamide (94%) and 88.6 kgs. of formalin (39.8%) in the presence of 10.35 kgs. of glacial acetic acid at temperatures between 70 and 80 C. The condensation product is deposited on the fiber as a white Water insoluble substance containing the zinc thiocyanate. The twill is rendered resistant against an attack of fungus and other causes of rotting. A similar effect is obtained by first saturating the twill with the aqueous solution of the condensation product and thereafter spraying the zinc thiocyanate solution on the fiber.

7. 126 grs. melamine heated with 345 cc. of a 37% formaldehyde solution for 5 minutes at a temperature of 80 C. and a pH between 9.0 and 9.3. The amorphous methylol compound is obtained by a careful atomizer v7 drying process and a 5% solution of this methylol compound prepared by addition of water. After standardization of the solution at a pH value of 7.3 by adding i.

phosphoric acid, 20% of zinc thiocyanate (relative value to the melamine condensate) are added. With this solution fabrics of cellulose fibers (for instance crash linen) are impregnated, and 10 minutes heated to a temperature of about into an insoluble fiber adhesive resin.

Having now described the means by which the objects of the invention are obtained, 1 claim:

1. A process for producing a fungicidal textile material composed of natural fibers comprising impregnating the material with a zinc thiocyanate solution,

2. A process as in claim 1, further comprising a 4% to 15% solution of zinc thiocyanate.

3. A process as in claim 2, further comprising impregnating said material with a 5% solution of aluminum sulphate.

4. A process as in claim 1, further comprising impregnating said material with a solution of 6% zinc thiocyanate and 8% solution of a soluble double salt of titanium.

120 C. whereby the solution is converted 5. A process as in claim 1, further comprising impregnating said material with a solution of 15% zinc thiocyanate and 4% of a basic zirconium acetate solution.

6. A process as in claim 1, further comprising impregnating said material with a water soluble, incompletely reacted, synthetic resin.

7. A process as in claim 1, further comprising first impregnating said material with a Water soluble, incompletely reacted, synthetic resin selected from the class consisting of dicyanodiamide and melamine, and then impregnating said material with zinc thiocyanate.

8. A fungicide resistant textile material comprising a material composed of natural fibers impregnated with zinc thiocyanate.

9. A fungicide resistant textile material comprising a material composed of natural fibers impregnated with a synthetic urea resin and zinc thiocyanate.

10. A fungicide resistant textile material comprising a material composed of natural fibers impregnated with a zinc thiocyanate solution and a solution selected from the group consisting of aluminum sulphate, a double salt of titanium, and basic zirconium acetate.

References Cited in the file of this patent UNITED STATES PATENTS 326,088 Alexanderson Sept. 15, 1885 1,434,549 Lewis et a1. Nov. 7, 1922 2,086,419 Hunt et a1. July 6, 1937 2,098,942 Brubaker Nov. 16, 1937 2,282,988 Creely May 12, 1942 2,289,064 OKane July 7, 1942 2,457,025 Benignus Dec. 21, 1945 

1. A PROCESS FOR PRODUCING A FUNGIDIAL MATERIAL COMPOSED OF NATURAL FIBERS COMPRISING IMPREGNATING THE MATERIAL WITH A ZINC THIOCYANATE SOLUTION. 